Study on “fracturing-sealing” integration technology based on high-energy gas fracturing in single seam with high gas and low air permeability

To improve the gas extraction efficiency of single seam with high gas and low air permeability, we developed the “fracturing-sealing” integration technology, and carried out the engineering experiment in the 3305 Tunliu mine. In the experiment, coal seams can achieve the aim of antireflection effect through the following process: First, project main cracks with the high energy pulse jet. Second, break the coal body by delaying the propellant blasting. Next, destroy the dense structure of the hard coal body, and form loose slit rings around the holes. Finally, seal the boreholes with the “strong–weak–strong” pressurized sealing technology. The results are as follows: The average concentration of gas extraction increases from 8.3% to 39.5%. The average discharge of gas extraction increases from 0.02 to 0.10 m3/min. The tunneling speeds up from 49.5 to 130 m/month. And the permeability of coal seams improves nearly tenfold. Under the same conditions, the technology is much more efficient in depressurization and antireflection than common methods. In other words, it will provide a more effective way for the gas extraction of single seam with high gas and low air permeability.